Screw lifting-jack.



- y i i .PATBNTED AUG. 1, 1905.

Y E. H. GO0DwIN.-

vSCREW LIFTING JACK. Y' APPLICATION FILED JAN.`] .'*,1905

WITNESSES."

UNITED STATES- ELI H. GOODWIN, OF OLYMPIA,VWASHINGTON, ASSIGNOR OF ONE-'HALF l PATENT OFFICE.

TO O. v. LINN, 0F OLYMPIA, WASHINGTON.

SCREW L||=T|NGJAGK.

- Specification of Letters Patent.

Patented A ug. 1, 1905.

Apphcation filed January 17, 1905. Serial No.24=l,418.

l lifting-power of the jack, and to prevent backing up of the screw-rod when the jack is un-` der a load.

The invention consists of 4novel features and parts and combinations of the same, as will be more fully described hereinafter and then pointed out'in the claims.

A practical embodiment of the invention is represented in the accompanying drawings, forming apart of this specification, in which similar characters of reference indicate correspondingparts in all the views.

Figure l is a side elevation of the improvement. elevation of the screw-rod and its head. Fig. 3 is a plan view of the same, the top member of the head being removed; and Fig. 4. is an enlarged perspective lview of one of the bearing-rollers.

In the stand A of the lifting-jack screws a screw-rod B, provided at its upper end with a head O, having a fixed member O', secured to the screw-rodV B, and a movable member O, adapted to engage with its top surface the load to be carried by the lifting-jack. Oonically-shaped friction-rollers D are interposed between the members C and C2 of the head O, and for this purpose the upper end of the iixed member O is provided with a` recess Oylfor receiving the friction-rollers D,

the bottom or bearing surfacel Ci ofthe recess O" being cone-shaped to corres-pond with the sides of the friction-rollers D. The bearingsurface OF on the under side of the rotating member ,C2 likewise corresponds with the sides of the rollers D, which latter are rounded od at their base ends to engage corresponding rounded-off portions on the surfaces O4 and O5 to prevent spreading of the rollers, thus avoiding undue friction, as the base-surfaces of the rollers cannot come in contact with the side wall of the recess O3. (See Fig.` 2.)

The rotating member O2 of the head O is proto be lifted and vheld against turning.

Fig. 2 is an enlarged sectional side vided with an annular flange O6, extending on the outside of the upper portion of the fixed member O', to act as a dust-cap in order to prevent Vdust'from passing to the bearing-surfaces and friction-rollers. The lower edge of the flange C6 is formed with ratchet-teeth O7, adapted to be engaged by a pawl E, fulcrumed on the fixed member O and serving to prevent accident-al return movement of the screw B vwhen the lifting-jack is under a load--that is,

when the member O2 is engaged with the part t 1s understood that when the member O2 is held against turning and the pawl E is in engagement with one of the ratchet-teeth O7 then the member O' and the screw-rod B are prevented from turning in a backward direction. The

fulcrum end of the pawl E is held in a bearing O8, formed integrally on the member C', fixedon the screw-rod, the said bearing limiting the downward swinging motion'ofthe pawl E.

Having th'us described my invention, I claim as new and desire to secure by Letters Patent-- l.- A lifting-jack comprising aV stand, a screw-rod screwing therein and provided with a head having a fixed and a rotating member, cone-shaped rollers interposed between the fixed and movable members, the bearing-surfaces of the said members conforming to the shape of the cone rollers, and a pawl-andratchet connection between the said members. 2. A-'lifting -jack comprising a stand, a screw-rod screwing therein and provided with a head having a fixed and a rotating member, and a pawl-and-ratchet connection between the said members, whereby accidental return movement of the screw-rod is prevented.

'3. A liftingjack, comprising a stand, a screw-rod, a two-part head on the upper end of the screw-rod, the lower part being fixed and having in its upper face a cone-shaped recess and the upper part being pivoted and having in its lower face a cone-shaped recess, the l lower part being also provided with an annular flange having teeth on its lower edge, coneshaped rollers in the recesses of the parts of the head, and a pawl pivoted to the iixed part of the head and engaging the ratchet-teeth of the upper part.

4. A lifting -jack comprising a stand, a screw-rod screwing therein and provided with a head having a fixed and a rotating member,

the latter havingan annular iiange fitting the outer upper portion of the fixed member, the

suriaees of the said members Conforming to the shape of the cone rollers.

In testimony whereof 1 have signed my mme to this speeilieation in the presence of two subscribing witnesses.

ELI H. GOODVV 1N Witnesses:

WALTER CROSBY, F. G. BLAKE. 

